Influence of welding parameters on the welding residual stresses

FE simulation of welds from austenitic steel was carried out in the current paper. Two different multi-pass welds were modelled. Measurements of welding residual stresses, which were found in literature, were applied for the validation of the results. The validated models were then used as basis for sensitivity analysis. The influence of differentiating the welding speed, the heat input of the weld heat source, intermediate cooling between consecutive weld-passes and welding sequence on the welding residual stresses was investigated

Correction to Residual stress relaxation in HFMI amp; 8209;treated fillet welds after single overload peaks

The article Residual stress relaxation in HFMI treated fillet welds after single overload peaks, written by Jan Schubnell, Eva Carl, Majid Farajian, Stefanos Gkatzogiannis, Peter Knödel, Thomas Ummenhofer, Robert Wimpory and Hamdollah Eslami, was originally published Online First without Open Access. After publication in volume 64, issue 6, page 1107 1117 the author decided to opt for Open Choice and to make the article an Open Access publication. Therefore, the copyright of the article has been changed to The Author s 2020 and the article is forthwith distributed under the terms of the Creative Commons Attribution Attribution 4. 0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author s and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http creativecommons.org licenses by 4.

Application of high frequency mechanical impact treatment to improve the fatigue strength of corroding welded joints

This study deals with the fatigue strength of high-frequency mechanical impact (HFMI)-treated unprotected structural details made of mild steel S355 considering the influence of corrosive environmental conditions. The investigations are carried out on butt welded specimens with sheet thickness t = 15 mm and on transverse non-load-carrying attachment specimens with sheet thickness t = 25 mm. Two different methods were applied for the simulation of marine corrosive environment in the laboratory. Specimens first were deposited in a salt spray chamber and then tested subsequently dry at laboratory-air conditions considering the influence of corrosion on the crack initiation. Alternatively, and to cover the effects of corrosion on the crack growth, artificial seawater was used for pre-corrosion, and after a defined timespan, fatigue tests were performed simultaneously with the specimen resting in the corrosive medium. The corrosion fatigue tests were performed in as-welded and HFMI-treated conditions at a stress ratio R = 0.1 under axial tensile and 4-point bending cyclic loading. The test results are evaluated to determine the characteristic fatigue strengths for fixed slopes m = 3 and m = 5 according to IIW recommendations for the as-welded and for the HFMI-treated condition respectively. The results of the experimental investigations based on the nominal stress approach show that the fatigue strength of both specimen types could be significantly increased by the application of HFMI treatment compared to the corresponding specimens in the as-welded condition even if exposed to the investigated corrosive conditions. The comparison with the design proposals of IIW shows that for HFMI-treated butt welds, no reduction of the FAT class due to corrosion is required and the recommended FAT class is still valid. The results for the HFMI-treated transverse attachments are slightly below the design curve recommended by IIW and a proposal to consider corrosion is derived for this case. Additional numerical investigations by applying the effective notch stress (ENS) approach are performed to determine notch stress curves. It was found that for the corroded specimens in the as-welded condition, the FAT class according to IIW could not be reached and adjustments of the existing rules are necessary to consider corrosion effects. However, it can be concluded that the effective notch fatigue resistance recommended by IIW is still applicable in the case of corroded HFMI-treated structural details

Influence of welding parameters on the welding residual stresses

FE simulation of welds from austenitic steel was carried out in the current paper. Two different multi-pass welds were modelled. Measurements of welding residual stresses, which were found in literature, were applied for the validation of the results. The validated models were then used as basis for sensitivity analysis. The influence of differentiating the welding speed, the heat input of the weld heat source, intermediate cooling between consecutive weld-passes and welding sequence on the welding residual stresses was investigated

Residual stress relaxation in HFMI treated fillet welds after single overload peaks

The induction of near surface compressive residual stress is an important factor for fatigue life improvement of HFMI treatedwelded joints. However, the relaxation of these beneficial residual stresses under single overload peaks under variable amplitude and service loads may significantly reduce fatigue life improvement. For this reason, several recommendations exist to limit the maximum applied load stress for this kind of post treated welded joints. In this work, the effect of single tension and compression overloads on the relaxation behavior of HFMI induced residual stresses was studied experimentally by means of X ray and neutron diffraction techniques complemented by numerical simulation at transverse stiffeners made of mild S355J2 steel and high strength S960QL steel. Loads were applied close to the real yield strength of the base material. Significantly different relaxation behavior was observed for S355J2 and S960QL steel. Furthermore, high compression loads lead to full residual stress relaxation at the weld toe of S960QL and moderate relaxation for S355J2. High tension loads lead only to slight relaxatio